Fluid handling equipment, whether the fluid is gas, liquid, combination of gas and liquid, slurries and so on, may use many fluid control devices that are connected together with the use of fittings. Typical fluid control devices include valves, regulators, meters and so on that are interconnected in a fluid circuit with either tube or pipe. The fittings may take on a wide variety of designs, including but not limited to single ferrule and multi-ferrule tube fittings, various clamping arrangements using elastomeric seals, gripping rings and so on. For purposes of this disclosure we refer to tube and pipe as “conduit” because the present invention may be used with either tube or pipe.
Common to nearly all fluid circuits that use fittings to connect conduit to a flow control device or process is the desire to verify in a non-destructive manner that a fitting has been fully assembled. Most connections via fittings involve the positioning of a conduit within a fitting body or other structure associated with a fluid coupling (referred to herein as a fitting assembly of a conduit and coupling) such that an end of the conduit abuts a shoulder or wall of the fitting body or other structure. This abutment or “bottoming” as we also refer to it herein, is usually desirable as it allows that gripping device, such as a ferrule, to be installed onto the conduit without the conduit moving axially.
Inherent in the assembly process, however, is the practical circumstance that once the fitting is installed there is no cost-effective non-destructive way, known to date, to determine that the conduit is fully bottomed. For example, it is known to use x-rays to observe the fitting condition, however, this is a very expensive process and simply not practical for many if not most assemblers. Various techniques are known that are used to verify proper installation of the fitting components, or to verify proper pull-up based on the number of turns of a fitting nut or axial displacement of the conduit relative to the nut. For example, the fitting may be disassembled after pull-up, visually inspected and then reassembled, but such steps are time consuming and costly. In another known technique, the tubing may be pre-marked in an appropriate manner prior to assembly, but this technique is subject to error in the marking or interpretation process. None of these techniques can absolutely determine in a final assembled fitting that the conduit is bottomed, and also determine the nature or quality of the contact or abutment between the conduit and the associated structure.
The need exists therefore to provide process and apparatus for non-destructive analysis and evaluation of whether a conduit is properly bottomed within a fitting.